The Princess Royal is expected to host members of the royal family for a special dinner on Friday evening, including the Prince and Princess of Wales, ahead of Trooping the Colour.
In her new role as Senior Colonel, Anne will head up a traditional dinner for her fellow Household Division Colonels on the eve of the King's birthday parade.
The Queen and the Princess of Wales were given military appointments last December, with Camilla made Colonel of the Grenadier Guards and Kate taking over her husband's role as Colonel of the Irish Guards.
Prince William is now Colonel of the Welsh Guards, following his father Charles's accession.
The Duke of Edinburgh and the Duke of Kent are also expected to attend as they are Royal Honorary Colonel, 1st Battalion London Guards and Colonel of the Scots Guards respectively.
The event usually takes place privately and was held at Clarence House last year.
It comes after Princess Anne joined her brother, the King, as he presented the Sovereign's Standard to The Blues and Royal at Buckingham Palace on Thursday. The Princess Royal is honorary Colonel of the regiment.
© Getty
© GettyThe royal siblings were both dressed in military uniform as they honoured the cavalry regiment.
Charles said in a speech: "It is a matter of great pride to be here with you today to present your New Standard, which represents that personal bond between The Blues and Royals and the Sovereign."
He added: "As your Colonel-in-Chief, I know that your Colonel, The Princess Royal, joins me in thanking you all for your unlimited commitment and service, as well as your families for their tremendous and unwavering support, some of whom I am delighted to see are able to join us today."
© GettyThe King's Cypher and Crown now appears on the new ceremonial standard which is made of silk damask, with gold thread embroidery and fringe.
It will be used for the first time in a public parade during Saturday's Trooping the Colour in which The Blues and Royals will have a starring role.
Charles will be joined by Anne, William and for the first time, Edward, as they ride on horseback during the parade.
© GettyIt will also mark the first time the reigning monarch has ridden at Trooping the Colour since 1986 when Queen Elizabeth II last rode. Take a look back at the late Queen's last ever birthday parade in the clip below...
Charles will take the salute as Colonel in Chief of the seven regiments of the Household Division during the event on Horse Guards Parade.
This year, the Welsh Guards' Colour will be trooped at The King’s birthday parade.
Meanwhile, Queen Camilla, the Princess of Wales and the Duchess of Edinburgh are expected to watch proceedings from carriages, before the royals gather on the Buckingham Palace balcony to watch the flypast.
